For those who haven't seen it already, here's Global Menu for GNOME Shell 3.2 in action (old video):

Before installing it, please read the following notes:

Global Menu for GNOME Shell is currently in alpha!

It only works with GTK applications (it may not even work with all GTK apps), so it won't work with Firefox, Thunderbird, LibreOffice, Java or even Qt apps;

it can crash GNOME Shell and you'll encounter bugs, including a bug that causes the windows for which the menu has been hidden to display a small gap where the menu used to be (this can be somewhat avoided by using a theme for which the gap is smaller, like Elementary for the titlebar and Zukitwo or Evolve GTK);

it may not work at all ;

I didn't create separate packages for each component, it's just one package that provides all the files. So if later on, GNOME Shell Global Menu will be uploaded to its official PPA, you'll have to remove this package.

3. Restart GNOME Shell (press ALT + F2 and enter "r") and activate GNOME Shell Global Menu extension using GNOME Tweak Tool, then log out and log back in. This is required and it won't work without logging out! If it still doesn't work, try a system restart.

Tip: if you want to launch an application without Global Menu, use the following command:

GTK_MODULES= APPLICATION-NAME

For example, to launch GIMP with the menu in its window and not on the top panel, use: